No E. coli was found in samples of beef burgers used in McDonald’s Quarter Pounders that have been linked to a deadly outbreak, a company spokesman said Sunday, citing tests by the Colorado Agriculture Department.
The department has no further plans to test the beef burgers, the company spokesman said, and the burgers have been ruled out as a source of the outbreak.
The most likely source of contamination was sliced onions from a single source, the company spokesman said, citing the Food and Drug Administration.
McDonald’s indefinitely stopped buying sliced onions from that source — Taylor Farms Colorado Springs — on Sunday, the company spokesman said, days after it removed Taylor Farms onions from its supply chain.
The Taylor Farms onions were sold in stores in Colorado, Kansas, Wyoming and parts of other nearby states, the spokesman said. Some of those locations include airports, which could explain cases in other states.
McDonald’s spokesman said the company is confident in asking beef suppliers to provide a fresh supply of burgers for distribution. Quarter Pounders are expected to be available in restaurants this week.
All 900 restaurants that receive onions from Taylor Farms Colorado Springs will continue to sell Quarter Pounders without onions for now, the company spokesman said.
No other burgers or McDonald’s menu items have been affected by the outbreak.
The strain of E. coli in the outbreak, called O157:H7, produces a potent toxin that can damage the lining of the small intestine.
The outbreak was first reported Tuesday, when the Centers for Disease Control and Prevention announced it was investigating an E. coli outbreak linked to McDonald’s Quarter Pounders in multiple states, prompting the fast-food chain to stop using chopped onions and quarter-pound beef burgers in several states, the agency said at the time.
The CDC reported Tuesday that the first E. coli case linked to McDonald’s occurred on Sept. 27. Colorado health officials alerted the CDC to an unusual increase in cases of the illness on Oct. 10. The agency launched an investigation on Oct. 15, Matt Wise, chief of the CDC’s Outbreak Response and Prevention Branch, told News.
The CDC focused its investigation on Wednesday on the onion chips at the Quarter Pounders. On Thursday, McDonald’s said the onions linked to the outbreak came from Taylor Farms.
On Wednesday, distributor U.S. Foods said Taylor Farms was recalling four raw onion products out of an abundance of caution due to “potential E. coli contamination.” The company urged its customers, including restaurants, to stop using them and destroy the affected products as soon as possible.
It also urged other restaurant chains in Colorado — including Illegal Pete’s and Taco Bell — to stop using onions on their menus.
A spokesman for Yum! Brands, Taco Bell’s parent company, said select Pizza Hut and KFC locations have also removed fresh onions from their menus. There have been no signs of E. coli illnesses linked to those restaurants.
The FDA said Thursday that it was investigating Taylor Farms as a possible source of the E. coli outbreak linked to the Quarter Pounders, but added that “we are investigating all possible sources.”
A Taylor Farms spokesperson did not immediately respond to a request for comment Sunday.
As of Friday, 75 people in 13 states had been infected with the E. coli strain and one person had died, the CDC said.
Twenty-two people have been hospitalized and two have developed hemolytic uremic syndrome, a serious complication that can cause permanent kidney failure or death.
Multiple people have sued McDonald’s, claiming they got sick after eating at the restaurant.